At least one person has been killed and an opposition leader injured in Sierra Leone in violent clashes at a political rally.

A local journalist, Patrick Jakema, told VOA Saturday the Sierra Leone People's Party was filing a formal complaint to demand an investigation into the previous day's events.

Both the SLPP and the ruling All People's Congress parties released statements Saturday condemning the violence.

Jakema said the clashes began Friday afternoon in the southern city of Bo. Julius Maada Bio, recently chosen by the SLPP to challenge President Ernest Koroma in next year's presidential poll, was marching through town with his supporters as part of a planned political rally.

He said that as the opposition group neared the local headquarters of the ruling party, they were pelted with stones and Bio was hit in the head and injured.

The violence escalated and the police shot into the air and tried to subdue the crowds.

At least 18 people were injured, and three buildings connected to the ruling party were set on fire.

SLPP's Bio was taken to a hospital but later returned to address the crowd.

Bio, a retired general, ruled Sierra Leone briefly in 1996 after seizing power in a coup.